Method apparatus and system for enhancing needle visualization in medical ultrasound imaging

ABSTRACT

The present invention discloses a method, apparatus and system for enhancing needle visualization in ultrasound imaging, said method comprising: a setting step for setting a scanning depth corresponding to a depth of a part or tissue target in a patient&#39;s body; and a determining step for automatically determining a needle frame steering angle and an ultrasound working frequency for needle frame collection based on the scanning depth. In the embodiments of the present invention, the needle frame steering angle and ultrasound working frequency for needle frame collection and the filter kernel for enhancing edge filtering of the collected needle frame are both dependent upon the scanning depth, and thereby can achieve enhancing needle visualization in ultrasound imaging for scanning at different depths without participation of the user or extra change of hardware.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/592,034, filed on Aug. 22, 2012, which claims foreign prioritybenefits to Chinese Application No. 201110270881.5, filed on Aug. 25,2011, all of which are incorporated by reference herein in theirentireties.

BACKGROUND OF THE INVENTION

Embodiments of the present invention relate to an ultrasound imagingtechnique, more particularly to a method, apparatus and system forenhancing needle visualization in medical ultrasound imaging atdifferent scanning depths.

In medical device ultrasound guidance application, the needlevisualization in ultrasound image is paramount for the clinician tosuccessfully perform an invasive ultrasound image guided procedure.

Needle visualization techniques in medical ultrasound systems, such as Bsteer, SteerXBeam and Expanded SteerXBeam, usually use one specialadditional frame called “needle frame” with fixed big steering angle andcollected by applying fixed ultrasound working frequency to visualizeand enhance the needle. If the needle guidance direction is vertical tothe steering angle for needle frame, needle visualization is enhanced.Otherwise, the needle will disappear or fade in the ultrasound image.

For example, the U.S. Pat. No. 6,524,247 entitled “Method and system forultrasound imaging of a biopsy needle” filed by Danhua Zhao et al. onMay 15, 2001 discloses a method for enhancing real time visualization ofa puncture needle, said method using a fixed scan angle (or a needleframe steering angle) to collect a needle frame. The Chinese patentapplication No. 201010624654.3 entitled “Method and apparatus forenhancing needle visualization in ultrasound imaging” filed by JianjunGuo et al. on Dec. 27, 2010 discloses a needle frame with a largesteering angle (e.g., 45°) and teaches that a plurality of framescollected by scanning at multiple angles, e.g., 25° and 45°, arecombined to yield a needle frame, thereby achieving optimum effect.

However, as patients differ greatly in figures, the same parts ortissues (e.g., heart) have different scanning depths in differentpatients, and different parts or tissues have different scanning depthsin the same patient as well. In the above-mentioned prior art, a fixedneedle frame steering angle is always used for ultrasound scanning atdifferent scanning depths, regardless of depth differences of differentscanned parts or tissues in patients. As a result, when the fixed needleframe steering angle is used to scan a large (e.g. obese) patient, theneedle is inserted into the patient's body substantially vertical toskin, such that the needle keeps substantially parallel to ultrasonicbeam, thereby causing the needle to disappear or fade in the ultrasoundimage. Hence, the needle frame collected with fixed needle framesteering angle and ultrasound working frequency in the prior art cannotsatisfy ultrasound guidance requirements at different depths.

Thus, it is necessary to provide a method, apparatus and system to avoidthe aforesaid problems and defects.

BRIEF DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide a method, apparatus andsystem operable to enhance needle visualization for scanning atdifferent depths by applying a depth-dependent needle frame steeringangle, ultrasound working frequency and edge enhancement filtering to aneedle frame.

According to an embodiment of the present invention, a method forenhancing needle visualization in ultrasound imaging is provided. Themethod comprises setting a scanning depth corresponding to a depth ofpart or tissue target in a patient's body; and automatically determininga needle frame steering angle and an ultrasound working frequency forneedle frame collection based on the scanning depth.

According to another embodiment of the present invention, an apparatusfor enhancing needle visualization in ultrasound imaging is provided.The apparatus comprises a setting module configured to set a scanningdepth corresponding to a depth of part or tissue target in a patient'sbody; and a determining module configured to automatically determine aneedle frame steering angle and an ultrasound working frequency forneedle frame collection based on the scanning depth.

According to another embodiment of the present invention, an ultrasoundimaging system comprising an apparatus for enhancing needlevisualization in ultrasound imaging is provided. The apparatus comprisesa setting module configured to set a scanning depth corresponding to adepth of part or tissue target in a patient's body; and a determiningmodule configured to automatically determine a needle frame steeringangle and an ultrasound working frequency for needle frame collectionbased on the scanning depth.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are specifically describedhereunder with reference to the figures and in combination with theembodiments. The same or similar elements in the figures are representedwith the same reference numerals. In the figures:

FIG. 1 illustrates a flowchart of a method for enhancing needlevisualization in ultrasound imaging according to one embodiment of thepresent invention;

FIG. 2 is a schematic diagram illustrating a case of applying the methodin FIG. 1 to a shallow depth according to one embodiment of the presentinvention;

FIG. 3 is a schematic diagram illustrating a case of applying the methodin FIG. 1 to a deep depth according to one embodiment of the presentinvention;

FIG. 4 illustrates a kernel configuration of an edge enhancement filterwhen the needle frame steering angle is 30°;

FIG. 5 illustrates a kernel configuration of an edge enhancement filterwhen the needle frame steering angle is 45°;

FIG. 6 is a schematic diagram illustrating an apparatus for enhancingneedle visualization in ultrasound imaging according to one embodimentof the present invention;

FIG. 7 is a schematic diagram illustrating another apparatus forenhancing needle visualization in ultrasound imaging according to oneembodiment of the present invention;

FIG. 8A illustrates a needle frame that is obtained according to theprior techniques in shallow depth applications;

FIG. 8B illustrates a needle frame that is obtained according to thetechnique of the present invention in shallow depth applications;

FIG. 9A illustrates a needle frame that is obtained according to theprior techniques in deep depth applications; and

FIG. 9B illustrates a needle frame that is obtained according to thetechnique of the present invention in deep depth applications.

DETAILED DESCRIPTION OF THE INVENTION

Many medical applications need ultrasound guidance of medicalinstruments like a needle to direct various invasive medical instrumentsto the part or tissue target within a patient's body. To direct theneedle to the part or tissue target safely and rapidly, it needs toenhance visualization of the needle in the ultrasound image.

A Needle is a highly reflective object. When the scan angle is verticalor substantially vertical to the needle angle, the needle visualizationin the ultrasound image is remarkable. In conventional medical imagingtechniques, a needle frame is used to enhance visualization of theneedle in the ultrasound image. A fixed big steering angle and a fixedultrasound working frequency are usually used to collect a needle frame.In the case of implementing medical instrument ultrasound guidance ondifferent patients, parameters including needle frame steering angle,ultrasound working frequency and filter settings will keep unchangedwhen the depth of the part or tissue target in the patient's bodychange, which influences enhanced visualization of the needle in theultrasound image.

Hence, according to the technique raised in the present invention,parameters like needle frame steering angle, ultrasound workingfrequency and/or filter settings are configured to be dependent upon thescanning depth corresponding to the depth of the part or tissue targetin the patient's body. In other words, according to the embodiments ofthe present invention, the needle frame steering angle and ultrasoundworking frequency for needle frame collection will changecorrespondingly when the scanning depth changes with the depth of thepart or tissue target in the patient's body.

According to one embodiment of the present invention, the method forenhancing needle visualization in ultrasound imaging further comprisesan enhancing step for performing edge enhancement filtering on acollected needle frame.

According to another embodiment of the present invention, a filterkernel for performing the enhancing step matches the determined needleframe steering angle for needle frame collection.

According to another embodiment of the present invention, a nonzerocoefficient is defined along a needle direction in the filter kernelmatching the needle frame steering angle for needle frame collection.

According to another embodiment of the present invention, a predefinedneedle frame steering angle and a predefined ultrasound workingfrequency corresponding to the scanning depth are searched in apre-stored table when performing the determining step as the needleframe steering angle and ultrasound working frequency for needle framecollection.

According to another embodiment of the present invention, the pre-storedtable comprises a plurality of predefined depth values, and a pluralityof predefined needle frame steering angles and a plurality of predefinedultrasound working frequencies respectively corresponding to each of theplurality of predefined depth values.

According to another embodiment of the present invention, the predefinedneedle frame steering angle and predefined ultrasound working frequencycorresponding to one of the plurality of predefined depth values that isequal or proximal to the scanning depth are determined as the needleframe steering angle and ultrasound working frequency for needle framecollection when performing the determining step.

According to another embodiment of the present invention, the shallowerthe scanning depth, the smaller the needle frame steering angle forneedle frame collection and the higher the ultrasound working frequencyfor needle frame collection.

According to another embodiment of the present invention, the deeper thescanning depth, the larger the needle frame steering angle for needleframe collection and the lower the ultrasound working frequency forneedle frame collection.

According to another embodiment of the present invention, the apparatusfor enhancing needle visualization in ultrasound imaging furthercomprises an enhancing module for performing edge enhancement filteringon a collected needle frame.

According to another embodiment of the present invention, a filterkernel used by the enhancing module matches the determined needle framesteering angle for needle frame collection.

According to another embodiment of the present invention, a nonzerocoefficient is defined along a needle direction in the filter kernelmatching the needle frame steering angle for needle frame collection.

According to another embodiment of the present invention, thedetermining module is configured to search for a predefined needle framesteering angle and a predefined ultrasound working frequencycorresponding to the scanning depth in a pre-stored table as the needleframe steering angle and ultrasound working frequency for needle framecollection.

According to another embodiment of the present invention, the pre-storedtable comprises a plurality of predefined depth values, and a pluralityof predefined needle frame steering angles and a plurality of predefinedultrasound working frequencies respectively corresponding to each of theplurality of predefined depth values.

According to another embodiment of the present invention, thedetermining module is further configured to determine the predefinedneedle frame steering angle and predefined ultrasound working frequencycorresponding to one of the plurality of predefined depth values that isequal or proximal to the scanning depth as the needle frame steeringangle and ultrasound working frequency for needle frame collection.

According to another embodiment of the present invention, the shallowerthe scanning depth, the smaller the needle frame steering angle forneedle frame collection and the higher the ultrasound working frequencyfor needle frame collection.

According to another embodiment of the present invention, the deeper thescanning depth, the larger the needle frame steering angle for needleframe collection and the lower the ultrasound working frequency forneedle frame collection.

According to another embodiment of the present invention, the apparatusfor enhancing needle visualization in ultrasound imaging furthercomprises or communicates with a memory for storing the table.

According to an embodiment of the present invention, the presentinvention provides an ultrasound imaging system comprising an apparatusfor enhancing needle visualization in ultrasound imaging according toanother embodiment of the present invention.

In the method, apparatus and system according to the embodiments of thepresent invention, the needle frame steering angle and ultrasoundworking frequency for needle frame collection and the filter kernel forenhancing edge filtering of the collected needle frame are bothdependent upon the scanning depth corresponding to the depth of the partor tissue target in a patient's body. When the scanning depth changeswith the depth of the part or tissue target in the patient's body, thepreferred needle frame steering angle and preferred ultrasound workingfrequency for needle frame collection will be adjusted automatically,and edge enhancement filtering dependent upon the scanning depth will beperformed on the collected needle frame, thereby achieving enhancedneedle visualization in ultrasound imaging for scanning at differentdepths without participation of the user, which facilitates improvingthe work flow of needle guidance in ultrasound imaging and saving thelatency time.

FIG. 1 illustrates a flowchart of a method 100 for enhancing needlevisualization in ultrasound imaging according to one embodiment of thepresent invention. As shown in the Figure, a scanning depthcorresponding to the depth of the part or tissue target in a patient'sbody is set at step 102. For example, when a clinician estimates thedepth of the part or tissue target in a patient's body at about 10 cm,he/she may set a scanning depth of about 15 cm via an interface suchthat the part or tissue target is approximately at a central position ofthe collected tissue frame and needle frame. Persons skilled in the artwill appreciate that the above data are just for demonstrative purposeand in no way limit the present invention.

At step 104, the scanning depth corresponding to the depth of the partor tissue target in a patient's body set at step 102 automaticallydetermines the needle frame steering angle and ultrasound workingfrequency for needle frame collection. For example, a predefined needleframe steering angle and a predefined ultrasound working frequencycorresponding to the set scanning depth can be searched in thepre-stored table as the needle frame steering angle and ultrasoundworking frequency for needle frame collection. The pre-stored table maycomprise a plurality of scanning depth values each corresponding to apredefined needle frame steering angle and a predefined ultrasoundworking frequency. Table 1 shows an exemplary tabulation.

Ultrasound Working Needle Frame Frequency Scanning Depth (cm) SteeringAngle (°) (MHz) . . . . . . . . . 1.0 15.0 15.0 2.0 20.0 13.0 3.0 . . .. . . 4.0 30.0 10.0 5.0 . . . . . . 6.0 40.0  8.0 . . . . . . . . .

Table 1 demonstratively provides a plurality of combinations of scanningdepth values, predefined needle frame steering angles and predefinedultrasound working frequencies. Persons skilled in the art willappreciate that the various combinations of the three parameters aslisted in the table are just for demonstration and in no way limit thepresent invention. For example, although the scanning depth values inthe table increase by a step length of 1.0 cm, persons skilled in theart will appreciate that the depth values can in fact increase by anyproper step length (e.g., 0.5 cm, 0.1 cm). The predefined needle framesteering angle and predefined ultrasound working frequency correspondingto a given depth value is dependent upon the attributes of relevantcomponents (e.g., a probe) in the ultrasound imaging system. The needleframe steering angle and ultrasound working frequency corresponding toeach of the depth values in Table 1 can be determined with experimentsand/or simulation.

Usually the smaller the scanning depth value, the smaller thecorresponding needle frame steering angle and the higher thecorresponding ultrasound working frequency; on the contrary, the largerthe scanning depth value, the larger the corresponding needle framesteering angle and the lower the corresponding ultrasound workingfrequency.

At step 104, if the depth value equal to the scanning depthcorresponding to the depth of the part or tissue target in a patient'sbody set at step 102 is not found in the table, the predefined needleframe steering angle and predefined ultrasound working frequencycorresponding to the depth value proximal to the scanning depth set inthe table shall be determined as the needle frame steering angle andultrasound working frequency for needle frame collection.

At the optional enhancing step 106, edge enhancement filtering isperformed on the collected needle frame. The Chinese patent applicationNo. 201010624654.3 entitled “Method and apparatus for enhancing needlevisualization in ultrasound imaging” filed by Jianjun Guo et al. on Dec.27, 2010 proposes a method for applying edge enhancement filteringtechnique to the collected needle frame with an edge enhancement filter.The contents of this patent application are integrally incorporatedherein by reference. FIG. 4 illustrates a kernel configuration of anedge enhancement filter when the needle frame steering angle for needleframe collection is 30°. FIG. 5 illustrates a kernel configuration of anedge enhancement filter when the needle frame steering angle for needleframe collection is 45°. As shown in the figures, the edge enhancementfilter kernel matches the needle frame steering angle for needle framecollection. That is, a nonzero coefficient is defined along the needledirection in the edge enhancement filter kernel, wherein the nonzerocoefficient can be, for instance, 1 but is not limited to 1.

As stated above, when performing edge enhancement filtering on thecollected needle frame, the edge enhancement filter kernel is configuredaccording to the needle frame steering angle for needle frame collectiondetermined at step 104, and the resulting edge enhancement filter kernelis then cross-correlated (convoluted) with the collected needle frame,thereby enhancing the needle signal in the needle frame and suppressingother tissue signals and artifacts in the needle frame. Besides, sincethe needle frame steering angle for needle frame collection is dependentupon the scanning depth corresponding to the depth of the part or tissuetarget in the patient's body, the edge enhancement filter kernelconfigured according to the needle frame steering angle is alsoconcerned with the scanning depth, and thereby can provide a lower levelof detection for shallower needles shown in FIG. 4 as well as a higherlevel of detection for deeper needles shown in FIG. 5.

Some embodiments of the present invention are further explained below incombination with FIGS. 2-3.

FIG. 2 illustrates a case of application to a shallow depth (e.g., smallor lean patients, or in vivo part or tissue target close to skin of apatient) according to one embodiment of the present invention. In thisembodiment, the part or tissue target is about 1.0 cm deep in apatient's body. Accordingly, the scanning depth can be set to be about2.0 cm. For shallow-depth applications, the part or tissue target andthe needle are normally located in a shallower field of an ultrasoundimage. In this case, the needle frame steering angle for needle framecollection will be configured as a small one which can enhance theneedle visualization in the ultrasound image and improve the overallultrasound image quality. In this embodiment, the needle frame steeringangle for needle frame collection is set to be 20.0°. In the meanwhile,a higher ultrasound working frequency will be used to increaseultrasound image resolution and needle appearance in such shallow-depthapplications. In this embodiment, the ultrasound working frequency forneedle frame collection is set to be the higher 13.0 MHz.

FIG. 3 illustrates a case of application to a deep depth (e.g., big orobese patients, or in vivo part or tissue target far from skin of apatient) according to one embodiment of the present invention. In thisembodiment, the part or tissue targets are about 2.0 cm deep in apatient's body. Accordingly, the scanning depth can be set to be about4.0 cm. For deep-depth applications, the part or tissue target and theneedle in a far field of the ultrasound image will interest theclinician. In this case, the needle guidance is very steep with a bigangle. Hence, the needle frame steering angle for needle framecollection should be configured as a large one to enhance ultrasoundsignal reflection from the needle. In this embodiment, the needle framesteering angle for needle frame collection is set to be 30.0°.

Limited by the acceptance angle of probe elements in the ultrasoundimaging system, a large needle frame steering angle will bringconsiderable noise and artifacts for the collected needle frame.Therefore, a lower ultrasound working frequency is applied in deep-depthapplications to expand the main lobe of a directivity function ofultrasound field, thereby decreasing noise and artifacts in the needleframe. In this embodiment, the ultrasound working frequency for needleframe collection is set to be the lower 10.0 MHz. Besides, a lowerultrasound working frequency in the deep-depth case will also increasethe ultrasound penetration of in vivo tissues to the part or tissuetarget and the needle at a deeper position in a patient's body, and thusfurther enhance needle visualization in the ultrasound image.

FIG. 6 illustrates a modularization block diagram of an apparatus 600for enhancing needle visualization in ultrasound imaging according toone embodiment of the present invention.

The apparatus 600 comprises a setting module 602 for setting a scanningdepth corresponding to a depth of the part or tissue target in apatient's body; and a determining module 604 for automaticallydetermining the needle frame steering angle and ultrasound workingfrequency for needle frame collection based on the set scanning depth.The shallower the set scanning depth, the smaller the needle framesteering angle for needle frame collection and the higher the ultrasoundworking frequency for needle frame collection. The deeper the setscanning depth, the larger the needle frame steering angle for needleframe collection and the lower the ultrasound working frequency forneedle frame collection.

The determining module 604 is configured to search for a predefinedneedle frame steering angle and a predefined ultrasound workingfrequency corresponding to the set scanning depth in a table stored by amemory 608 as the needle frame steering angle and ultrasound workingfrequency for needle frame collection. Specifically, the determiningmodule 604 is configured to use the predefined needle frame steeringangle and the predefined ultrasound working frequency corresponding tothe depth value equal or proximal to the set scanning depth in the tableas the needle frame steering angle and the ultrasound working frequencyfor needle frame collection.

The apparatus 600 optionally comprises an enhancing module 606 forperforming edge enhancement filtering on the collected needle frame,wherein a nonzero coefficient, e.g., 1 but not limited to 1, is definedalong the needle direction in a filter kernel matching the needle framesteering angle for needle frame collection.

The apparatus 600 may further comprise or communicate with a memory 608for storing a table necessary for determining the needle frame steeringangle and the ultrasound working frequency for needle frame collectionbased on the set scanning depth. The table comprises a plurality ofpredefined depth values, and a plurality of predefined needle framesteering angles and a plurality of predefined ultrasound workingfrequencies respectively corresponding to each of the plurality ofpredefined depth values.

One or more modules in the apparatus 600 as shown in FIG. 6 can beimplemented by software, hardware, firmware or combination(s) thereof.

FIG. 7 is a schematic diagram illustrating another apparatus 700 forenhancing needle visualization in ultrasound imaging according to oneembodiment of the present invention. As shown in the figure, theapparatus 700 comprises a processing unit 702 such as MCU, DSP or CPU.The processing unit 702 may comprise one or more units to performdifferent steps of the method in FIG. 1. The apparatus 700 may furthercomprise or communicate with a memory 704 for storing the tablementioned above. The apparatus 700 optionally comprises an interface 706for inputting a set scanning depth and collected needle image data; andan output unit 708 for outputting processed needle image data.

The apparatus 600 or 700 for enhancing needle visualization inultrasound imaging according to the above embodiments can be implementedby software, hardware, firmware or combination(s) thereof in variousultrasound imaging systems.

FIG. 8A illustrates a needle enhancement image that is obtainedaccording to the prior techniques in shallow depth applications; andFIG. 8B illustrates a needle enhancement image that is obtainedaccording to the technique of the present invention in shallow depthapplications. In the shallow depth applications, the scanning depth isset as 2 cm. As shown in the figures, the needle visualization obtainedaccording to the technique of the present invention is remarkablyenhanced as compared with the needle enhancement image that is obtainedaccording to the prior techniques.

FIG. 9A illustrates a needle enhancement image that is obtainedaccording to the prior techniques in deep depth applications; and FIG.9B illustrates a needle enhancement image that is obtained according tothe technique of the present invention in deep depth applications. Inthe deep depth applications, the scanning depth is set as 6 cm. As shownin the figures, the needle visualization obtained according to thetechnique of the present invention is remarkably enhanced as comparedwith the needle enhancement image that is obtained according to theprior techniques.

The foregoing is a detailed description of the present invention by wayof specific embodiments. However, specific embodiments of the presentinvention should not be construed as limited to the description. It willbe appreciated by those skilled in the art that various modifications,equivalent substitutions, and changes may be made to the presentdisclosure. For example, the function may be achieved by dividing onestep or module in the above embodiments into two or more steps ormodules; or on the contrary, the functions of two or more steps ormodules in the above embodiments may be achieved within one step ormodule. As long as the alterations do not depart from the spirit of thepresent disclosure, they should be considered within the protectionscope of the present invention. Besides, some terms in the descriptionand claims of the present application are not limitative butdescriptive. In addition, “one embodiment”, “another embodiment” etc.used for many times above refer to different embodiments, and candefinitely be entirely or partly incorporated in one embodiment.

The invention claimed is:
 1. A method for enhancing needle visualizationin ultrasound imaging, the method comprising: setting a scanning depthcorresponding to a depth of a part or tissue target in a patient's body;and automatically determining a needle frame steering angle and anultrasound working frequency for needle frame collection based on thescanning depth.
 2. The method according to claim 1 further comprisingperforming edge enhancement filtering on a collected needle frame. 3.The method according to claim 2, wherein a filter kernel for performingedge enhancement filtering matches the determined needle frame steeringangle for needle frame collection.
 4. The method according to claim 3,wherein a nonzero coefficient is defined along a needle direction in thefilter kernel matching the needle frame steering angle for needle framecollection.
 5. The method according to claim 1, wherein automaticallydetermining a needle frame steering angle and an ultrasound workingfrequency further comprises searching for a predefined needle framesteering angle and a predefined ultrasound working frequencycorresponding to the scanning depth in a pre-stored table.
 6. The methodaccording to claim 5, wherein the pre-stored table comprises a pluralityof predefined depth values, and wherein the pre-stored table comprises aplurality of predefined needle frame steering angles and a plurality ofpredefined ultrasound working frequencies respectively corresponding toeach of the plurality of predefined depth values.
 7. The methodaccording to claim 6, wherein automatically determining a needle framesteering angle and an ultrasound working frequency further comprisesdetermining the predefined needle frame steering angle and predefinedultrasound working frequency corresponding to one of the plurality ofpredefined depth values that is equal or proximal to the scanning depth.8. The method according to claim 1, wherein the shallower the scanningdepth, the smaller the needle frame steering angle for needle framecollection and the higher the ultrasound working frequency for needleframe collection.
 9. The method according to claim 1, wherein the deeperthe scanning depth, the larger the needle frame steering angle forneedle frame collection and the lower the ultrasound working frequencyfor needle frame collection.